Navigation Links
Microbial 'cheaters' help scientists ID 'social' genes

HOUSTON, Feb. 13, 2008 -- The first genome-wide search for genes governing social behavior has found that even the simplest social creatures -- the amoebae Dictyostelium discoideum -- have more than 100 genes that help regulate their cooperative behavior.

The study by scientists at Rice University and Baylor College of Medicine (BCM) was published online this week by the journal Nature. It marks one of the first large-scale attempts to combine evolutionary biology with genomics in a systematic search for genes tied to social behavior.

"This pool of genes is going to allow us to understand the genetic architecture of social behavior," said co-author Joan Strassmann, Rice's Harry C. and Olga K. Wiess Professor of Ecology and Evolutionary Biology.

Though little understood, social cooperation among microbes causes major medical and industrial problems. Medically, cooperation underlies conditions as mundane as tooth decay to more serious conditions like chronic infections associated with medical implants. Industrially, slimy colonies of bacteria also foul filters at water treatment plants and other facilities, causing millions of dollars of damage each year.

Rice and BCM's genome-wide investigation took five years and required the detailed study of some 10,000 randomly mutated strains of D. discoideum. "The basic idea was to knock out genes at random and put each mutant through 10 rounds germination, growth and development to identify mutations that led to cheating," Strassmann said.

Cheating mutations were found in more than 100 genes. Since there are advantages to be gained from cheating, Strassmann said the real mystery, from an evolutionary point of view, is how species like D. discoideum manage to keep cheaters from out-producing and eliminating cooperation altogether.

"This is just the beginning," said co-author Adam Kuspa, BCM's S. J. Wakil Chair of Biochemistry and Molecular Biology. "Now we need to define key molecular mechanisms that might serve to stabilize cell cooperation."

Strassmann said, "Cheating is to be expected. Cooperation is the real story. Since cheaters can thrive without these 100-plus genes, there has to be some other reason that they're still in the genome."

D. discoideum are a common soil microbe. Their social order is one of the simplest in nature and it's an oft-used laboratory model for sociality. Though loners in times of plenty, D. discoideum form colonies when food is scarce, and work collectively to ensure their survival. About one fifth of the colony's individuals form a tall, thin stalk. The rest climb the stalk and clump together into a small bulb that can be carried away to better environs by the wind or on the legs of passing insects.

This simple social system poses an evolutionary conundrum for biologists; the individuals in the stalk give themselves up altruistically to support the colony, so what's to keep more selfish strains of D. discoideum from cheating the system, avoiding the stalk and out-reproducing their altruistic neighbors?

Strassmann and co-authors Gad Shaulsky, associate professor of molecular and human genetics at BCM, and David Queller, Rice's Harry C. and Olga K. Wiess Professor of Ecology and Evolutionary Biology, have identified a handful of cheater mutations for D. discoideum in prior studies. However, identifying cheaters was just the start in the genome-wide study. Cheaters were also subjected to additional tests so the team could find out how exactly how they cheated. The scientists also examined the cheaters' genetic code to locate the precise site of the cheater mutations.

The tests found that cheaters would exploit virtually any advantage to increase their share of spores in the next colony. While strategies for cheating varied at the proteomic level, the study found some cheaters use a common genetic strategy -- they piggyback onto other essential functions. In a previous study, Strassmann and colleagues had identified a cheater that used the same strategy, and she said the broader study indicates that the "dual-function strategy" may be shared by other successful cheaters.

"The evolutionary opportunities for moves and countermoves appear to create a kind of genetic arms race in which cheating mutations are met with counter-mutations," Strassmann said. "In this arena, cheating is often going to be piggybacked onto essential functions, making it hard to get rid of and hard to control."


Contact: Jade Boyd
Rice University

Related medicine news :

1. Virginia Techs Raving First Year Results Lead to Additional High-Tech Antimicrobial Defense from SportCoatings(TM)
2. Replidyne Pipeline Featured at 47th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy
3. Stress Robs Skin of Antimicrobial Defenses
4. Scientists seek to assess the microbial risks in the water we drink
5. Microban International Partners with Magic American Products to Launch Magic(R) Brand Products with Microban(R) Antimicrobial Product Protection
6. Seal Shield Ships New SILVER SEAL(TM) Washable, Antimicrobial Keyboard
7. New prion protein discovered by Canadian scientists may offer insight into mad cow disease
8. Scientists Probe Sepsis Deadly Secrets
9. Scientists puzzled by severe allergic reaction to cancer drug in the middle Southern US
10. Scientists Develop Natural Protection for Stored Foods
11. Scientists detect presence of marburg virus in african fruit bats
Post Your Comments:
(Date:11/25/2015)... ALTO, Calif. (PRWEB) , ... November 25, 2015 , ... ... Smart and Beddit Classic sleep tracking systems. The new app features a more intuitive ... see and understand how well you slept. The SleepScore is created by a proprietary ...
(Date:11/25/2015)... LOUIS, Missouri (PRWEB) , ... November 25, 2015 ... ... Project HEAL, will provide scholarships for people struggling with eating disorders as a ... Proceeds from the second annual event, held at Fox Run Golf Club in ...
(Date:11/25/2015)... ... November 25, 2015 , ... Many people know of the common ... cold hands, and dry skin. But many people who find their cholesterol levels and ... instead of their thyroid, especially if they don’t have any of the other symptoms. ...
(Date:11/24/2015)... ... November 25, 2015 , ... ... Their Care Plan software creates an agreement between the practice owner and ... including financial, scheduling, monitoring, notification, and projections. Click here to ...
(Date:11/24/2015)... Texas (PRWEB) , ... November 24, 2015 , ... Charitable ... all charitable donations are made in the last five weeks of the year totalling ... was created in 2012 to connect the nation’s charities with those individuals who want ...
Breaking Medicine News(10 mins):
(Date:11/25/2015)... SAN DIEGO , Nov. 25, 2015  Trovagene, ... molecular diagnostics, today announced that Chief Executive Officer Antonius ... at the 27 th Annual Piper Jaffray Healthcare ... Conference at the New York Palace Hotel in ... 2015 at 1:30 p.m. EST. Mr. Schuh will be ...
(Date:11/25/2015)... Endo International plc (NASDAQ: ENDP ) (TSX: ... and CEO, will discuss corporate updates at the 27 th ... York on Wednesday, December 2, 2015 at 1 ... Relations, and then the link to the event. Participants should ... to visit the site and download any streaming media software ...
(Date:11/25/2015)... Israel , November 25, 2015 ... "New Investors"), pursuant to which BioLight and the New ... IOPtima Ltd. subsidiary ("IOPtima") via a private placement. The ... of its innovative IOPtimate™ system used in the treatment ... approval pathway process for the IOPtimate™ system with the ...
Breaking Medicine Technology: